Composition cork and the manufacture thereof



EEQ'UE CKE, OF BARCELONA, SPAIN,ASSIGNOR TO MANUFACTURAS DE CORCHO S. .A. O]? BARCELONA, SPAIN, A LIMITED CORPORATION OF SPAIN.

COMPOSITION CORK AN D THE MANUFACTURE THEREOF.

Ho Drawing.

This invention relates to improvements-in the art of manufacturing composition cork in the form of thin sheets or webs and to the improved product resulting therefrom. The

object of the invention is to produce an improved sheet or web of composition cork of superior quality which may be used without splitting or skiving for such purposes as gaskets and other packings, bottle closures 0 and the like and in fact any purpose for which thin sheets of cork are desirable.

The physical properties of cork are such as to render it a highly desirable material for many industrial uses such as packings, heat and sound insulation, floor coverings and the like. but in its natural state the size and shape of the pieces of cork bark and the varying quality thereof are such as to seriously limit its use. In view of-these facts, cork has for many years been made up into blocks, slabs, rods or heavy sheets, by assembling What is commercially termed granulated cork with or without a'binder and subjecting the same to heat and pressureto compact the mass and unite the particles one to another. The heating of cork particles to a suficiently high temperaturejor example, from 500 F.to 600 F, drives ofi moisture and partially volatilizes and otherwise liberates the inherent resinous matter contained in the cork and causes at least part of the resinous matter to be so disposed in relation .to the surfaces of the cork particles as to act as a binder when the part1- cles are subjected to pressure to hold them one to another and to protect the exposed surfaces of the particles so as to close and efiectively seal the natural pores or cells and render the cork product substantially non-absorptive and less permeable than natural cork.

49 But whenever these blocks, slabs, rods or heavy sheets are cut, split or skived to form disks, thin sheets or other articles, as they commonly are to obtain pieces of usable dimensions, the particles of cork are divided by the cutting knife so as to expose new surfaces which are not protected by'the resinous matter and the product again becomes absorptive and more permeable. This is particularly true and particularly detrimental in the'case 59 of thin, sheets or disks wherein a single particle may be thus exposed on both sides of the sheet or disk.

It haslong been known that when ,cork

particles are subjected to a sufiiciently high degree of temperature to cause the inherent produce thin moulded sheets Application filed November 22, 1923. Serial No. 676,291.

cementitious matter to function as a binder, for example, to a temperature varying from 500 to 500 F or even higher, the cork gives ofi' various gases equaling many times itsv volume. It cork particles are so heated and slmuleaneously subjected to pressure the forces generated by the liberation of gases are tremendous and the gases should be permltted to escape at least in part. In the manufacture of composition cork in the form of blocks, slabs, heavy sheets, rods and the hke, moulds with loose fitting parts are commonly used so that the gases generated by the applledheat may pass through the relatively thlck mass of 'cork to the crevices between the mould parts and thereby escape. Heretofore the problem of disposing of the gases so generated has rendered it impossible, in so far as I am aware, to produce in a commerclally satlsfactory manner relatively thin sheets er webs of composition cork under such .conditlons of temperature and pressure as will liberate the natural same effective as a binding and protective material.

It is an object of the present invention to I of composition cork, that 1s, sheets moulded to usable thickness of about three-sixteenths of an inch or less and not necessarily split or skived, and 1n whlch the resinous matter inherent in the cork has been rendered efi'ective to bind the part cles together and render the product relatively non-absorptive and impermeable. Such sheets may even be sandths of an inch.

In the practice of the present invention the cork 1s' first subdivided into relatively small particles or obtained in that form, that is to say, particles preferably having at least one dlmension not exceeding the thickness of the finlshed sheet by more than the extent of or inherent resinous matter contained 1n the cork and render the as thin as four-thoucompression to which the cork particles are to be subjected. For example, if the cork particles are to be compressed one-sixth, it

i is desirable that at least one dimension shall not be more than six times greater than the thickness of the'finished sheet. Preferably the particles are selected so that at least one dimension will be somewhat less than above stated in order that'in the finished sheet the particles may more certainly partially overlie one another. The preferred form of cork particle used has a substantial surface area escape and be in relation its thickness as for instance a substantially flat particle formed by shaving or chipping the natural cork.

In carrying out the invention a layer of cork particles several times the thickness of the finished sheet is formed upon a suitable support so that the same may be subjected.to the necessary heat and pressure. If desired, suitable cementitiousmaterial may be mixed with the cork particles, but preferably the natural resinous matter contained in the cork itself is alone relied upon to cement the particles together. If it is desired to form a continuous web this layer of cork particles may be introduced between cooperating. endless conveyors which are urged toward each other by suitable pressure means or if separate sheets are to be formed the cork may be introduced between the platens of a suitable press provided with means for heating and cooling the platens. The volatile gases formed when the cork is subjected to heat are permitted to escape directly from the surface of the sheet or web and preferably from the entire surface, as, for example, by interposing a piece of fine mesh wire cloth between the cork and the smooth surfaced platen of the press preferably on both sides of the cork. When the platens of the press are brought together under sufficient pressure to compress the cork, for instance, to one-sixth or even to one-twentieth of its original volume, the cork will be pressed into the interstices of the metal cloth but on the opposite side where the cloth comes in contact with the smooth surface of the platen, .minute passages will be left open by which the gases generated when heat is applied can dissipated from the edges of the press.

Preferably the cork particles are subjected to a temperature of approximately 575 F.

. while under pressure and for a time dependin upon the thickness of the material. With a t in gasket material of a thickness of about one-sixteenth of an inch, the heat and ressure will need to be maintained only or a very short time because the cork, due to the thinness of the sheet, will readily heat through and the resinous matter will be partly volatilized and otherwise liberated so as to firmly cement one particle of cork to another and so dispose .of the resinous matter in relation to the surface of the sheet as to render the product more nearly impermeable than presently known products. The amount of ressure to which the cork particles are sub ected may be varied within wide limits and Wlll depend upon the quality, form and condition of the cork particles, upon the ex tent to which it is desired to compress the cork relatively to its natural state and upon the character desired for the finished pr0dnot and the use for which it is intended.

Preferably the cork is cooled while being .maintained under pressure, as by the intro- .duction of a suitable heat exchange medium into the platens of the press when a platen press is used or by moving the conveyors to a cooling station if a continuous web is being formed.

Thin sheeted cork produced in accordance with and embodying the present invention perceptibly flat- Furthermore, the naliberated by the applied heat will pores will be closed and effectively sealed.

Inasmuch as cork sheets of the present invention may be produced in such thin sheets as are ordinarily required for gaskets and other packings, bottle closures and the like, these various particles may be died out from the sheets without the splitting or skiving which has heretofore been necessary. The present process also overcomes the difliculties of thoroughly heating through a substantially thick body of cork material in the manufacture of composition cork.

It is to be understood that the present invention is not limited to the precise method of procedure or to the product described above for illustration but may be variously modified and embodied within the scope of the subjoined claims.

I claim as my invention:

1. The improvement in the art of manufacturing composition cork in relatively thin individually moulded sheets, which consists in subjecting a thin layer of cork particles to heat and pressure over a substantial area and ermitting the escape directly from the surace of the sheet of gases formed by the applithereon.

2. The improvement in the art of manufac- J turing composition cork in relatively thin individually moulded sheets not exceedin three-sixteenths of an inch in thickness, which consists in subjecting a thin layer of cork particles to heat and pressure over a substantial area and permitting the escape directly from the surface of the sheet of gases formed b the application of heat while maintaining t e pressure thereon.

3. The improvement in the art of manufacturing composition cork in relatively thin individually moulded sheets, which consists in subjecting a thin layer of cork particles to heat and pressure over a substantial. area, permitting the escape directly from the sursure thereon, and thereafter cooling saidmoulded sheet while maintaining the pressure thereon.

4. The improvement in the art of manufacturing composition cork in relatively thin individually moulded sheets, which consists in subjecting a thin layer of cork particles to heat and pressure over a substantial area and permitting the escape directly from the entire surface of the sheet of gases formed by the application of heat while maintaining the pressure thereon.

5. The improvement in the art of manufacturing relatively thin individually sheeted composition cork which consists in subjecting a thin layer of cork particles to sufficient pressure over a substantial area to materially compress the same, simultaneously subjecting said particles to suflicient heat to cause the same to be firmly united one to another and, while said heat and pressure is being maintained, permitting the gases formed by the application of heat to escape from the surface of the cork.

6. The improvement-in the art of manufacturing composition cork in relatively thin individually moulded sheets, which consists in assembling a thin layer of cork particles adjacent a fine mesh wire cloth, and sub ecting said particles while so maintained to the action of heat and pressure.

7. The improvement in the art of manufacturing composition cork in relatively thin individually moulded sheets, which consists in forming a thin layer of cork particles be- 4 tween coextensive screens of fine mesh wire cloth, and. subjecting the cork particles to heat and pressure while so maintained.

8. As an article of manufacture, an individually moulded sheet of composition cork not exceeding three-sixteenths of an inch in thickness and comprising a multiplicity of cork particles united by heat and pressure, with permissible escape of gases.

9. As an article of manufacture, an indi-' vidually moulded sheet of composition cork not exceeding three-sixteenths of an inch in thickness and comprising a multiplicity of cork particles bound to one" another solely by their inherent cementitious matter.

10. As an article of manufacture, 'an individually moulded sheet of cork comprisin a multiplicity of adhering particles moul ed under heat and pressure with accompanying liberation of gases to a usable thickness not exceeding three-sixteenths of an inch and having its surfaces rendered substantially impermeable by the resinous matter inherent in the cork.

In testimony whereof, I have signed my name to this specification this 21st day of November, 1923.

' ENRIQUE VINCE. 

